1. Field of the Invention
The present invention relates to a thermoelectric conversion element and a thermoelectric conversion material used in the same element.
2. Description of the Related Art
In recent years, in consideration of the global environment, there has been a demand for the transition of fossil energies of the related art into renewable energies. Examples of the renewable energies include solar power generation, wind power generation, wave power generation, vibration power generation, thermoelectric power generation, and the like, however, among the above-described power generations, the thermoelectric power generation is attracting attention since the thermoelectric power generation is capable of directly converting thermal energy into electric power, and is capable of effectively using a huge quantity of unused thermal energy such as exhaust heat from solar power generation, geothermal power generation, hot water heat power generation, an industrial furnace or a vehicle. In addition, the thermoelectric power generation is capable of directly converting thermal energy into electric power, and does not require a movable unit, and thus has been put into practical use of a wrist watch which is operated by using body heat, a power supply in a remote area, a power supply in the space, and the like.
For the thermoelectric power generation, a thermoelectric conversion material capable of converting thermal energy into electric energy and vice versa, and a thermoelectric conversion element (thermoelectric power generation element) produced by processing the thermoelectric conversion material are used. From the viewpoint of the thermoelectric conversion efficiency, the thermoelectric conversion material that has been put into practical use at the moment is an inorganic material, but the inorganic material has problems of a high price, the inclusion of a harmful substance, the complicated step of being processed into a thermoelectric conversion element, and the like. Therefore, studies are underway regarding an organic thermoelectric conversion material that can be manufactured at a relatively low cost, and can be easily formed into a film. For example, US2010/0319750A and JP2008-3050831A report thermoelectric conversion materials for which a carbon nanotube is used.